1. Field of the Invention
The present invention relates generally to devices used to generate a vacuum, and in particular to devices used to vacuum organic material such as leaves, cut grass, small sticks, pine needles, wood chips, nuts and other agricultural produce (hereinafter referred to as "organic material").
2. Description of the Prior Art
In order to vacuum organic material from an area, an impeller is disposed within a housing, an inlet duct is connected to the housing near the low pressure side of the impeller, and an outlet duct is connected to the housing near the high pressure side of the impeller. The impeller is normally driven via a drive shaft by a motor such that a vacuum is created in the inlet duct and a positive pressure is generated in the outlet duct. Organic material to be removed from an area is sucked into the inlet duct, moves through the housing, and then to the outlet duct where the organic material is blown by the impeller normally, but not always, to a container. When vacuuming organic material from an area, unwanted hard objects such as rocks and large sticks (hereinafter referred to as "hard objects") are often sucked along with the organic material into the inlet duct.
In the prior art devices used to vacuum organic material, impellers are rigid since they are generally made from metal or inflexible plastic. The hard objects sucked into the inlet duct often impact the impeller at a velocity high enough to damage the impeller and/or drive shaft, or the hard objects are wedged between the rigid impeller and the housing, which can cause damage to the impeller, motor, drive shaft, and housing.
The metallic prior art impellers are heavy. This results in a need for proper dynamic balancing of the impeller. Impacting the impeller with hard objects or wedging hard objects between the housing and the impeller can cause the impeller to go out of balance, thereby increasing operation costs due to lost time and costs associated with replacing or rebalancing the impeller. The weight of the prior art impellers also necessitates strong (and therefore heavy) support structures.
Furthermore, to reduce the chance that hard objects will become wedged between the housing and the impeller, the prior art devices sometimes provide a large clearance space between the housing and the tips of the impeller blades. Such a space results in generating less vacuum than could be generated with a smaller space between the housing and the impeller.
Also in the prior art, it is difficult to alter the direction in which the outlet duct directs the organic material. If it is desired to blow the organic material in a different direction, either (1) another duct must be attached to the outlet duct, or (2) several nut/bolt assemblies must be removed, the duct turned and the nut/bolt assemblies reinstalled. Either of these means of changing the direction in which the organic material is blown is time consuming and cumbersome.
Finally, in the prior art, a hand-held tube is provided for connecting to the inlet duct. These hand-held tubes are usually simple tubes having an external collar with handles so that the end of the tube can be positioned near the organic material by an operator. The entrances of these hand-held tubes are prone to plugging by sticks or other material caught on the entrance edge. Furthermore, a straight edge entrance results in significant loss of vacuum. In addition, to properly position the entrance of a prior art hand-held tube near organic material, the user is often required to bend downward, thereby causing back strain.